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Determining the effects of a mixture of an endocrine disrupting compound, 17a-ethinylestradiol, and ammonia on fathead minnow (Pimephales promelas) reproduction
Citation:
Armstrong, B., Jim Lazorchak, C. Murphy, H. Haring, K. Jensen, AND M. Smith. Determining the effects of a mixture of an endocrine disrupting compound, 17a-ethinylestradiol, and ammonia on fathead minnow (Pimephales promelas) reproduction. CHEMOSPHERE. Elsevier Science Ltd, New York, NY, 120(2):108-114, (2015).
Impact/Purpose:
The paper reports an interesting finding in that acute toxicity was found in a mixture of an EDC and a conventional pollutant, yet no chronic toxicity was found.
Description:
Aquatic organisms are exposed to a multitude of contaminants and to fully understand the impact of multiple stressors on fish populations, we must first understand the mechanism of action for each toxicant and how the combined effects manifest at the level of the individual. 17α-ethinylestradiol (EE2) has been known to cause adverse reproductive effects including reduced fecundity and fertility, intersex and skewed sex ratios in fish by mimicking naturally produced estrogen at low concentrations. Ammonia can cause adverse reproductive and mortality effects in individual fish through effects or damage to the central nervous system. Both EE2 and ammonia are found in most municipal effluents in various concentrations. A flow-through diluter system was used to test the individual effects of these two contaminants at their respective no-observable-adverse-effect (NOEC) level as well as their mixture on fathead minnow reproduction. The mixture of EE2 and ammonia at their NOEC resulted in significant mortality. Neither contaminant nor their mixture caused adverse effects on reproduction in terms of egg production. This finding confirmed the estimated no observable effect concentration proposed by Armstrong et al. (2012); 0.025 mg/L un-ionized ammonia (2.19 mg/L total ammonia-nitrogen) as the un-ionized ammonia concentration tested in this study, 0.034 mg/L (2.26 total ammonia-nitrogen), did not cause a significant reproductive effects. This study demonstrated the need for toxicity testing with multiple stressors.
